1. Field of the Invention
This invention relates to a blade-opening arrowhead having at least one blade which is pivotally mounted to move between a fully open position and a fully closed position wherein there is a positive snap locking blade retention system that maintains each blade in a normally closed position.
2. Description of Prior Art
In the archery industry, many manufacturers have attempted to simultaneously achieve an arrowhead that has aerodynamic properties similar to those associated with non-bladed arrowheads known as field points or nib points, while also achieving effective cutting areas provided by bladed arrowheads, which are often referred to as broadheads. Broadhead blades which are exposed during flight often result in undesirable steering of the front portion of the arrow, causing the arrow to deviate from a perfect flight path that coincides with a longitudinal axis of the arrow shaft, when loaded or drawn within an archery bow.
By reducing the surface area of a broadhead blade, the undesirable steering effects can be reduced. However, when the surface area of a blade is significantly reduced, the structural integrity is diminished. Also, by reducing the surface area of a blade, the cutting area within a target or game is also reduced, resulting in a less effective entrance and exit wound.
Conventional blade-opening arrowheads have been designed so that a substantial portion of the blade is hidden within the body of the arrowhead, such as during flight of the arrow. Upon impact, such blades are designed to open and thereby expose a cutting surface or sharp edge of the blade. When the blades of such conventional arrowheads are closed and substantially hidden within the body, the exposed surface area is reduced and thus produces relatively less undesirable steering effects.
Many of such conventional blade-opening arrowheads rely upon complex mechanisms, some of which fail to open because of a significant holding or closing force that must be overcome, and others that open prematurely because of structural deficiencies within the blade carrying body that fail upon impact, resulting in non-penetration of the arrow. With such relatively complex mechanisms, dirt or other materials that may enter such conventional arrowheads can affect the reliability of the arrowhead, particularly after prolonged use.
Other conventional broadheads which have blades partially hidden within the body use annular retaining rings, such as O-rings, wraps, bands and the like, in order to maintain the blades in a closed position during flight. Upon impact, such annular retaining rings are designed to sheer or roll back along the opening blades, in order to allow the blades to move to an open position. Quite often, such conventional annular retaining rings are prone to cracking, particularly when the elastomer material dries out. Upon release of a bowstring, the rapid acceleration and thus significant opening forces move the blades in an opening direction. The conventional annular retaining rings counteract such opening forces. However, when the ring material dries out, cracks or is otherwise damaged, the blades may open prematurely, resulting in significant danger or injury to the archer.
Many of the annular retaining rings are designed for one use and thus must be replaced after each use. In addition to the cost involved with supplying such consumable item, the annular retaining rings are difficult and time-consuming to install, such as when hunting, particularly during inclement weather. Furthermore, the material properties of such conventional annular retaining rings can be affected by temperature changes, thereby resulting in different bias forces that cause the blade to open prematurely or to not open when desired.
U.S. Pat. No. 5,090,709 teaches an arrowhead with extendable blades positioned adjacent fixed blades. The extendable blades are pivotally connected to a body. A ring releasably holds the extendable blades within corresponding slots within the body.
U.S. Pat. No. 5,286,035 teaches an arrowhead that has a sharpened blade, pivotally mounted within a slot in the body of the arrowhead. A rubber O-ring is used to hold the blade in a temporarily stationary position, centered within the slot in the body. Upon impact, the rubber O-ring slides rearward onto the arrow shaft and allows the blade to pivot to either side of the arrowhead body.
U.S. Pat. Nos. 5,112,063, 4,998,738 and 5,082,292 disclose a broadhead with deployable cutting blades that are connected by pivot pins to a plunger. The cutting blades pivot between an open cutting position and a closed non-barbed position.
U.S. Pat. No. 5,102,147 discloses a ballistic broadhead assembly that has blades pivotally mounted on an actuating plunger. Upon impact, the actuating plunger thrusts the blades outwardly and forwardly.
It is apparent from the conventional blade-opening arrowheads that there is a need for a blade-opening arrowhead that maintains each blade in a closed and locked position during flight, and that allows the blades to responsively free-wheel to an open position when a sufficient opening force is applied to the blade. It is also apparent that there is a need for a blade-opening arrowhead that does not require consumable items, such as O-rings, wraps, bands and the like, to hold the blades in a closed position.